This study investigated the association of enzyme-producing microbes and their enzymes with starch and hemicellulose degradation during fermentation of total mixed ration (TMR) silage. The TMRs were prepared with soybean curd residue, alfalfa hay (ATMR) or Leymus chinensis hay (LTMR), corn meal, soybean meal, vitamin-mineral supplements, and salt at a ratio of 25:40:30:4:0.5:0.5 on a dry matter basis. Laboratory-scale bag silos were randomly opened after 1, 3, 7, 14, 28, and 56 days of ensiling and subjected to analyses of fermentation quality, carbohydrates loss, microbial amylase and hemicellulase activities, succession of dominant amylolytic or hemicellulolytic microbes, and their microbial and enzymatic properties. Both ATMR and LTMR silages were well preserved, with low pH and high lactic acid concentrations. In addition to the substantial loss of water soluble carbohydrates, loss of starch and hemicellulose was also observed in both TMR silages with prolonged ensiling. The microbial amylase activity remained detectable throughout the ensiling in both TMR silages, whereas the microbial hemicellulase activity progressively decreased until it was inactive at day 14 post-ensiling in both TMR silages. During the early stage of fermentation, the main amylase-producing microbes were Bacillus amyloliquefaciens (B. amyloliquefaciens), B. cereus, B. licheniformis, and B. subtilis in ATMR silage and B. flexus, B. licheniformis, and Paenibacillus xylanexedens (P. xylanexedens) in LTMR silage, whereas Enterococcus faecium was closely associated with starch hydrolysis at the later stage of fermentation in both TMR silages. B. amyloliquefaciens, B. licheniformis, and B. subtilis and B. licheniformis, B. pumilus, and P. xylanexedens were the main source of microbial hemicellulase during the early stage of fermentation in ATMR and LTMR silages, respectively. The microbial amylase contributes to starch hydrolysis during the ensiling process in both TMR silages, whereas the microbial hemicellulase participates in the hemicellulose degradation only at the early stage of ensiling.

The objective of this study was to evaluate the effect of Pediococcus pentosaceus inoculation on the fermentation quality and the dynamics of microbial communities during ensiling and aerobic exposure in total mixed ration (TMR) silage. The TMR were prepared using alfalfa (Medicago sativa L.), maize meal, soybean curd residue, soybean meal, calcium carbonate, vitamin‐mineral supplement and salt (60.0:21.4:15.0:2.0:1.0:0.5:0.1, dry matter basis) with or without P. pentosaceus inoculation (10⁵ cfu/g fresh matter) followed by 14 or 28 days of ensiling and exposed to air. Microbial communities were detected by high‐throughput sequencing. After ensiling, P. pentosaceus inoculation benefited silage fermentation as indicated by increased lactic acid content and decreased pH, whereas had no effect on aerobic stability. Taxonomic bacterial community was dominated by Lactobacillales after ensiling, with a notable increase in spoilage microorganisms as a result of aerobic exposure. Aerobically exposed TMR was characterized by an increase of operational taxonomic units belonging to the Hypocreales and with yeast genus Cryptococcus, whereas Monascus was the major mold genus in the aerobically exposed silages. Candida was detected with higher relative abundance only in 28 days aerobically exposed sample inoculated with P. pentosaceus. P. pentosaceus inoculation has good effects on improving the fermentation quality and shows a potential to inhibit the proliferation of Monascus at 28 days of ensiling.